Pulp and papermaking operations have always been concerned with the problem of organic deposits. These organic deposits comprise various sticky materials which may originate from the anionic resinous materials present in the wood from which the paper is made, or may originate from various inks or adhesive materials which are present in recycled paper which is frequently being used in current paper making processes. The organic deposit material originating naturally from the wood is referred to as "pitch" whereas the organic deposit material originating from recycled fiber is referred to as "stickies". However, for purposes of this invention, the term "pitch" shall include not only naturally occurring pitch particles derived from paper pulp, but also any synthetic sticky materials derived from recycled fiber and which form insoluble organic deposits on paper making equipment surfaces.
Pitch is known to accumulate at various points in the papermaking system. For example, it is known to block the paper machine felts and thus hinder drainage of the paper web. It can adhere to the wires or drying cylinders causing it to pick holes in the paper. It may also deposit on press rolls, dryer fabric or other like equipment surfaces which come into direct or indirect contact with the aqueous pulp suspension, paper sheet or paper machine felts. In fact, all paper machine fabrics and many of the rolls which contact the fabrics or paper sheet will, from time to time, accumulate pitch deposits.
Many materials and techniques have been used in an attempt to eliminate these problems. A traditional technique to control these deposits has been to shut down the production equipment to clean off the affected equipment parts with various solvents. Alternative methods involve the treatment of the aqueous pulp system with various chemical dispersants including inorganic dispersants such as talc or anionic dispersants. These dispersants are of course added in amounts which are effective to disperse the pitch particles in the aqueous pulps suspensions. However, the use of these conventional dispersants has been generally ineffective, particularly in closed papermaking systems where the system water is continuously recycled and results in the accumulation and build-up of pitch in the system (known as cycling up). In such closed systems the pitch particles must be removed from the system water in a controlled way without being allowed to accumulate on the paper machine equipment such as the felts, rolls, or the pipe works.
One such method of controlled removal is to spray aqueous formulations of cationic polymers and cationic surfactants onto paper machine surfaces which are prone to pitch deposit formations to reduce the build-up of these deposits. However, this method has not been completely successful for controlling deposits on paper machines or other related paper making operations which use pulp suspensions containing relatively high dosages of cationic wet strength resins, cationic sizing agents, cationic dyes or other cationic treatment agents which are present in amounts which provide a neutral or cationic soluble charge to the normally anionic soluble charge of the aqueous pulp suspension.